Forming using the casting machine includes injecting a molten metal into a mold and pressurizing the metal until it is solidified. This method has been widely used because of accuracy of a cast product, reduction in culling machining, etc.
As shown in FIGS. 7 and 8, a conventional die casting machine can be classified into a horizontal type die casting machine in which a molten metal (melted liquid) is moved horizontally and a vertical type die casting machine in which the molten metal is moved vertically. In the horizontal type die casting machine, when a molten metal is horizontally injected into the mold by a plunger, minute bubbles are generated due to severe occurrence of a turbulent flow in a L-shaped bend portion (T) of FIG. 7. Meanwhile, in the vertical type die casting machine, when a molten metal is horizontally injected into the mold by the plunger, minute bubbles are generated due to severe occurrence of a turbulent flow in a L-shaped bend portion (Q) of FIG. 8.
Therefore, minute bubbles are generated in a product. It is difficult to obtain a product of a good quality and to product a product of a high quality as a conventional die casting machine due to lots of defective products.
In addition, there was disclosed a conventional vacuum apparatus of a die casting machine for producing a product of a high quality in a vacuum state by shutting an alloy of a high melting point, which is easily oxidized by oxygen in air, from oxygen in air. Referring to FIG. 16, the conventional vacuum apparatus has a construction in which a fixed mold 100, a movable mold 200, a support rod 400 into which an induction coil coolant circulating pipe 110 and a power supply cable 900 are inserted, a melted liquid crucible 300 to which a high frequency induction coil 800 is fixed, and nippers 500 for injecting a material into the melted liquid crucible 300 are surrounded by one vacuum tank 600. In this construction, however, lots of time is taken to evacuate the interior of the vacuum tank 600 by means of the vacuum pump 700. Also, the degree of vacuum within the vacuum tank 600 is not good Therefore, there is a problem that a product of a good quality is not produced using an alloy of a high melting point that is easily oxidized in air.